Solid recovered fuels — Determination of self-heating — Part 1: Isothermal calorimetry

This document specifies an analytical method for quantification of the spontaneous heat generation from solid recovered fuels using isothermal calorimetry. This document gives guidance on the applicability and use of the specified analytical method. It further establishes procedures for sampling and sample handling of solid recovered fuels prior to the analysis of spontaneous heat generation. The test procedure given in this document quantifies the thermal power (heat flow) of the sample during the test. It does not identify the source of self-heating in the test portion analysed.

Combustibles solides de récupération — Détermination de l'auto-échauffement — Partie 1: Détermination calorimétrique isotherme

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Status
Published
Publication Date
14-Nov-2022
Current Stage
6060 - International Standard published
Due Date
19-May-2022
Completion Date
15-Nov-2022
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ISO 21911-1:2022 - Solid recovered fuels — Determination of self-heating — Part 1: Isothermal calorimetry Released:15. 11. 2022
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INTERNATIONAL ISO
STANDARD 21911-1
First edition
2022-11
Solid recovered fuels — Determination
of self-heating —
Part 1:
Isothermal calorimetry
Combustibles solides de récupération — Détermination de l'auto-
échauffement —
Partie 1: Détermination calorimétrique isotherme
Reference number
ISO 21911-1:2022(E)
© ISO 2022
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ISO 21911-1:2022(E)
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© ISO 2022

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© ISO 2022 – All rights reserved
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ISO 21911-1:2022(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction .................................................................................................................................................................................................................................v

1 S c op e ................................................................................................................................................................................................................................. 1

2 Nor m at i ve r ef er enc e s ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 P r i nc iple ........................................................................................................................................................................................................................ 2

5 A pp a r at u s .................................................................................................................................................................................................................... 2

6 S a mple ha nd l i n g ...................................................................................................................................................................................................3

6.1 General ........................................................................................................................................................................................................... 3

6 . 2 S a mpl in g ....................................................................................................................................................................................................... 4

6.3 S ample transport and storage .................................................................................................................................................. 4

6 .4 S a mple pr ep a r at ion ............................................................................................................................................................................ 4

7 Te s t pr o c e du r e .......................................................................................................................................................................................................4

7.1 Temp er at u r e s t abi l i z at ion ........................................................................................................................................... ................. 4

7.2 S ample vial preparation ................................................................................................................................................................. 4

7. 2 .1 P r ep a r at ion pr o c e du r e ................................................................................................................................................. 4

7.2.2 Procedure to find proper test portion in case of influence from oxygen

deficiency .................................................................................................................................................................................. 5

7.3 R eference vial preparation .......................................................................................................................................................... 5

7.4 Me a s u r ement ........................................................................................................................................................................................... 6

7.4.1 F irst baseline measurement ..................................................................................................................................... 6

7.4 . 2 S a mple me a s u r ement ..................................................................................................................................................... 6

7.4.3 Second baseline measurement .............................................................................................................................. 6

7.4.4 M easurement data file ................................................................................................................................................... 6

8 R e s u lt s ........................................................................................................................................... .................................................................................. 6

8 .1 Te s t d at a ....................................................................................................................................................................................................... 6

8 . 2 R ep or t e d d at a .......................................................................................................................................................................................... 7

9 Te s t r ep or t .................................................................................................................................................................................................................. 7

Annex A (normative) Calibration of the calorimeter ......................................................................................................................... 8

Annex B (informative) Example of isothermal calorimetric measurements of solid

recovered fuel ......................................................................................................................................................................................................10

Bibliography .............................................................................................................................................................................................................................12

iii
© ISO 2022 – All rights reserved
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ISO 21911-1:2022(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 300, Solid recovered materials, including

solid recovered fuels.
A list of all parts in the ISO 21911 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www.iso.org/members.html.
© ISO 2022 – All rights reserved
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ISO 21911-1:2022(E)
Introduction

There is a continuous global growth in the trading and use of solid recovered fuels (SRFs). This has

resulted in an increased probability of fires, which has consequences for the handling, transporting

and storage of SRFs.

SRFs can generate heat spontaneously by exothermic biological, chemical and physical processes. The

heat build-up can be significant in large storage volumes if the heat conduction in the material is low. In

some conditions the heat generation can lead to pyrolysis and spontaneous ignition. The potential for

self-heating varies considerably for different types and qualities of SRFs and it is important to be able to

identify SRF fractions with high heat generation potential to avoid fires in stored materials.

The increasing number of incidents is a clear indicator that safety needs to be prioritized, first of all

for human safety and environmental concerns but also because interruptions in energy supply will

have significant consequences. SRF fires throughout the supply chain will also, in addition to safety and

environmental issues and direct economic losses, have a negative impact on the confidence in the SRFs

as a reliable energy source. They can also lead to difficulties in obtaining insurance coverage.

It is difficult for SRF producers, logistics providers, SRF users, equipment suppliers and manufacturers,

consultants, authorities and insurance providers to determine reasonable safety measures and an

appropriate level of protection due to a lack of standards and recommendations.

As part of the determination and the assessment of risks for SRFs, defined test methods and standards

are established or need to be developed. However, ageing and degradation due to the handling and

storage of SRFs in actual environments affects their characteristics, so safety margins should be

established in relation to actual analysis results.

The test method described in this document, isothermal calorimetry, is a method where the heat flow

generated from the test portion is measured directly. The operating temperature for an isothermal

calorimeter is normally in the range of 5 °C to 90 °C (some calorimeters can reach even higher

temperatures) and can therefore measure low-temperature reactions, such as those from bacteria and

other microbes. However, isothermal calorimetry is used for monitoring the thermal activity or heat

flow of chemical, physical and biological processes. The technique is most commonly used in the fields

of pharmaceuticals, energetic materials and cement. Isothermal calorimetry has also been applied for

[6]–[10]
the measurement of heat flow from the self-heating of solid biofuel pellets .

For investigating heat generation at high temperatures, other types of test methods, such as basket

heating tests, are possibly more suitable.

Data on spontaneous heat generation determined using this document are only associated with the

specific quality, composition and age of the sample material.

The information derived using this document is for use in quality control and in hazard and risk

assessments.
© ISO 2022 – All rights reserved
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INTERNATIONAL STANDARD ISO 21911-1:2022(E)
Solid recovered fuels — Determination of self-heating —
Part 1:
Isothermal calorimetry
1 S cope

This document specifies an analytical method for quantification of the spontaneous heat generation

from solid recovered fuels using isothermal calorimetry.

This document gives guidance on the applicability and use of the specified analytical method. It further

establishes procedures for sampling and sample handling of solid recovered fuels prior to the analysis

of spontaneous heat generation.

The test procedure given in this document quantifies the thermal power (heat flow) of the sample

during the test. It does not identify the source of self-heating in the test portion analysed.

2 Normat ive references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 21637, Solid recovered fuels — Vocabulary
ISO 21645, Solid recovered fuels — Methods for sampling
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 21637 apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
analysis temperature
temperature of the analysis environment, i.e. the calorimeter temperature
3.2
self-heating

rise in temperature in a material resulting from an exothermic reaction within the material

[SOURCE: ISO 13943:2017, 3.341, modified — “” removed from the definition.]

3.3
test portion

sub-sample of either a laboratory sample (3.5) or a test sample (3.4) required for the specific

measurement
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ISO 21911-1:2022(E)
3.4
test sample
laboratory sample (3.5) after an appropriate preparation made by the laboratory
3.5
laboratory sample
part of the sample sent to or received by the laboratory
3.6
thermal power
rate of heat flow produced by the sample during the test
Note 1 to entry: Expressed in W or J/s.

Note 2 to entry: Commonly also expressed as specific thermal power with reference to the unit mass of solid

recovered fuel in W/g or J/(s·g).
4 Principle

Isothermal calorimetry is one of the sensitive techniques for studying heat production or heat

consumption from samples of different kinds. It is non-destructive and non-invasive to the sample. Heat

production due to any physical, chemical or biological changes in a sample can be measured. When heat

is produced or consumed by any process, a temperature gradient is developed across the sensor. This

will generate a voltage, which is proportional to the heat flow across the sensor and to the rate of the

process taking place in the sample ampoule. The signal is recorded continuously and in real time.

NOTE 1 A commercial instrument for isothermal calorimetry normally has multiple channels and can thus be

used for measurements of several samples simultaneously.

For each sample (channel) there is an inert reference that is on a parallel heat-flow sensor. During

the time that the heat flow is monitored, any temperature fluctuations entering the instrument will

influence both the sample and the reference sensors equally. This architecture allows a very accurate

determination of heat that is produced or consumed by the sample alone while other non-sample-

related heat disturbances are efficiently removed. The measured heat flow is normalized against the

mass of the sample and the result is expressed in mW/g.

NOTE 2 The operating temperature for an isothermal calorimeter is typically in the range of 5 °C to 90 °C.

However, there are calorimeters with a somewhat higher span for operating temperature.

5 Apparatus
The usual laboratory apparatus and, in particular, the following shall be used.
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ISO 21911-1:2022(E)

5.1 Isothermal calorimeter, consisting of a sample holder for the sample vial and the reference

vial, each thermally connected to heat-flow sensors, which are thermally connected to a constant

temperature sink. See example in Figure 1.
Key
1 thermostat 4 reference
2 heat sink 5 heat-flow sensors
3 sample
Figure 1 — Schematic drawing of an isothermal calorimeter

The calorimeter shall be calibrated for the analysis temperature according to Annex A, Clauses A.1, A.2

and A.3. The analysis temperatures for the screening test procedure are 50 °C and 70 °C.

The data acquisition equipment shall be capable of performing continuous logging of the calorimeter

output measured at time intervals of less than or equal to 10 s.

The baseline shall exhibit a low random noise level and be stable against drift, according to Annex A,

Clause A.4.
The minimum sensitivity for measuring power output shall be 100 µW.

5.2 Sample vial, made of glass with a minimum volume of 20 ml and provided with an airtight lid

with an inert seal. Vials with volumes larger than 20 ml can be used if the sample loading is scaled

accordingly (see 7.2.2). In such cases, this deviation from the standard procedure is noted in the test

report.
5.3
...

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